Add a dependency on rake.

Gemfile.lock

@@ -0,0 +1,47 @@
+PATH
+  remote: .
+  specs:
+    bourbon (1.4.0)
+      sass (>= 3.1)
+
+GEM
+  remote: http://rubygems.org/
+  specs:
+    aruba (0.4.11)
+      childprocess (>= 0.2.3)
+      cucumber (>= 1.1.1)
+      ffi (>= 1.0.11)
+      rspec (>= 2.7.0)
+    builder (3.0.0)
+    childprocess (0.3.1)
+      ffi (~> 1.0.6)
+    cucumber (1.1.9)
+      builder (>= 2.1.2)
+      diff-lcs (>= 1.1.2)
+      gherkin (~> 2.9.0)
+      json (>= 1.4.6)
+      term-ansicolor (>= 1.0.6)
+    diff-lcs (1.1.3)
+    ffi (1.0.11)
+    gherkin (2.9.0)
+      json (>= 1.4.6)
+    json (1.6.5)
+    rake (0.9.2.2)
+    rspec (2.8.0)
+      rspec-core (~> 2.8.0)
+      rspec-expectations (~> 2.8.0)
+      rspec-mocks (~> 2.8.0)
+    rspec-core (2.8.0)
+    rspec-expectations (2.8.0)
+      diff-lcs (~> 1.1.2)
+    rspec-mocks (2.8.0)
+    sass (3.1.15)
+    term-ansicolor (1.0.7)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  aruba (~> 0.4)
+  bourbon!
+  rake

bourbon.gemspec

@@ -29,4 +29,5 @@ that support only CSS3 prefixed properties.
   s.add_dependency('sass', '>= 3.1')
 
   s.add_development_dependency('aruba', '~> 0.4')
+  s.add_development_dependency('rake')
 end